Student life in London

I am thinking of applying to KCL as I really like the course but I am nervous about meeting people and making friends etc... if not in a campus uni. Do people still socialise in London or do most people commute in because of the cost of halls? I can't live at home as it's too far to commute and was hoping to meet other freshers. Also concerned about the cost of accommodation in the second year. Do people live in private halls in second and third years - these look really expensive?